Theoretical electronic structure with spin-orbit coupling effect of the molecules SrAt and BaAt for laser cooling studies.

Ab initio CASSCF/MRCI + Q calculations have been used to investigate the electronic structure and transition properties of the alkaline earth astatine molecules SrAt and BaAt. The adiabatic potential energy curves have been computed and plotted for the low-lying electronic states in the representations 2S+1Λ+/- and Ω(±) (with and without spin-orbit coupling effect). The spectroscopic and vibrational constants have been deduced for the corresponding bound states. An analysis of the Franck-Condon factors, the Einstein Coefficients, and the branching ratios among different vibrational levels has shown that both SrAt and BaAt molecules are suitable candidates for Doppler and Sysphus laser cooling. Experimental laser cooling schemes and conditions for these two molecules have been proposed. These results may pave the way for new spectroscopic and laser cooling experiments of alkaline earth astatine molecules.

Laser cooling and electronic structure of Be halide anions BeX- (X = Cl, Br, F, and I).

The adiabatic potential energy curves of the low lying electronic states of the Be halide anions BeX- (Cl, Br, F, and I) have been investigated in the representation 2s+1Λ(+/-) by using the complete active space self-consistent field with a multireference configuration interaction method. The spectroscopic parameters Te, Re, ωe, and Be and the static and transition dipole moment µe were studied, and a rovibrational study of the investigated electronic states was performed. New electronic states were investigated here for the first time. The calculated highly diagonal Franck-Condon factor and the short radiative lifetime among the lowest vibrational levels of the X1Σ0+ - (1)3Π1 transitions of the molecular anion BeF- prove its candidacy for Doppler laser cooling. The experimental proof of the stability and the calculated experimental parameters, such as the vibrational branching ratio, the slowing distance, the recoil, and Doppler temperatures with the experimental conditions of the buffer gas cell of this anion, open the route for experimental work on the BeF- molecular ion.

Laser Cooling with an Intermediate State and Electronic Structure Studies of the Molecules CaCs and CaNa.

The ground and excited electronic states of the diatomic molecules CaCs and CaNa have been investigated by implementing the ab initio CASSCF/(MRCI + Q) calculation. The potential energy curves of the doublet and quartet electronic low energy states in the representation 2s+1Λ(±) have been determined for the two considered molecules, in addition to the spectroscopic constants T e, ωe, B e, R e, and the values of the dipole moment µe and the dissociation energy D e. The determination of vibrational constants E v, B v, D v, and the turning points R min and R max up to the vibrational level v = 100 was possible with the use of the canonical functions schemes. Additionally, the transition and the static dipole moments curves, Einstein coefficients, the spontaneous radiative lifetime, the emission oscillator strength, and the Franck-Condon factors are computed. These calculations showed that the molecule CaCs is a good candidate for Doppler laser cooling with an intermediate state. A "four laser" cooling scheme is presented, along with the values of Doppler limit temperature T D = 55.9 µK and the recoil temperature T r = 132 nK. These results should provide a good reference for experimental spectroscopic and ultra-cold molecular physics studies.

A theoretical electronic structure with a feasibility study of laser cooling of LaNa molecules with a spin orbit effect.

The electronic structure with the spin orbit effect of the molecule LaNa has been studied in the present work using the Multi-Reference Configuration Interaction MRCI calculations including Davidson correction (+Q). Adiabatic potential energy curves (PECs) have been investigated for the lowest low-lying spin free states in the Λ representation and spin orbit states of Ω = 0+/-, 1, 2, 3, and 4 along with their spectroscopic constants Re, Te, ωe, and Be, the dissociation energy De, the dipole moment µe, and the ionic character fionic of the LaNa molecule at the equilibrium bond length. The permanent dipole moment curves (PDMCs) for the investigated states are calculated in addition to the electronic transition dipole moments between the lowest electronic states where the Franck-Condon factor (FCF) has been calculated for the X1Σ+-11Π and for many spin orbit transitions. For these transitions the dipole moments are used in order to determine the Einstein coefficient of spontaneous emission Aν'ν, the radiative lifetime τ and the branching ratio Rν'ν. Employing the canonical function approach, the rovibrational parameters Eν, Bν, Dν, Rmin and Rmax have also been calculated for the lowest vibrational levels of different bound states in both Λ and Ω representations. To the best of our knowledge, the data reported in the present work are presented for the first time in the literature with a discussion on the candidacy of this molecule for laser cooling.

Electronic Structures and Transition Properties of BeSe and BeTe Molecules.

The electronic structure of BeSe and BeTe molecules has been investigated using the ab initio CASSCF/(MRCI + Q) method at the spin-free and spin-orbit level. The potential energy curves, the permanent dipole moment, the spectroscopic constants T e, R e, ωe, and B e, and the dissociation energy D e are determined in addition to the vertical transition energy Tv. The molecules' percentages of ionic character are deduced, and the trends of the spectroscopic constants of the two molecules are compared and justified. A ro-vibrational study is performed using the canonical function approach to calculate the constants E v, B v, and D v and the turning points R min and R max. All the ground-state vibrational levels have also been investigated. The radiative lifetimes of vibrational transitions among the electronic ground states are also discussed. The results for BeSe have been compared with the previously published data while those for BeTe molecules are presented here for the first time.

Ab-initio calculations of the electronic structure of the alkaline earth hydride anions XH- (X = Mg, Ca, Sr and Ba) toward laser cooling experiment.

By the use of the ab initio CASSCF/(MRCI+Q) calculations in the representation 2s+1Λ(+/-), the adiabatic potential energy curves and the dipole moment curves of the low lying states of the alkaline earth hydride anions (MgH-, CaH-, SrH- and BaH-) have been investigated in their singlet and triplet multiplicities. The spectroscopic parameters Te, Re, ωe, Be, αe, the dipole moment µe, and the dissociation energy De have been also calculated for the bound states of the considered molecules. In addition, a systematic investigation of the transition dipole moment curves for the lowest 1Σ+-1Π transitions has been done along with the Franck-Condon factor (FCF) corresponding to the X1Σ+-(1)1Π transition. Using the canonical function approach, a rovibrational study has been performed for finding the rovibrational constants Ev, Bv, Dv and the turning points Rmin and Rmax for the ground and different excited bound state. Efficient routes may be achieved via the diagonal FCF for the formation of cold and ultracold alkaline earth hydride anions. PACS N: 31.10. + z, 31.15.A, 31.15.vn, 31.50.Df.